Process for reducing iron ores



May 17, 1949. v. F. PARRY- PROCESS FOR REDUCING IRON oREs Original Filed April 20, 1945 l /f//l//f Patented May 17, 1949 UNITED STATES PATNT OFFICE Original application April 20, 1945, Serial No. 589,450. Divided and this application October 7, 1946, Serial No. 701,634

(Granted under the act of March 3. 1883, as amended April 30. 1928; 370 O. G. 757) 1 Claim.

The invention described herein may be manufactured and used by or for the GovernmentI of the United States for governmental purposes without the payment to me of any royalty thereon in accordance with the provisions of the act of April 30, 1928 (Ch. 460, 45 Stat. L. 467).

This invention relates to chemical reaction methods, and, more particularly, to suitable methods for carrying out endothermic chemical reactions involving solid and gaseous materials, such as the gasification of lignite with concomitant reduction of iron ore.

Accordingly, this invention has for its object the provision of a method for the reduction of iron ores with concomitant gasiiication of noncoking solid carbonaceous materials wherein high heat economies are achieved in a continuous In accordance with this invention, a non-coking solid carbonaceous material, such as lignite, is gasied and iron ore is reduced by an endothermic chemical process which comprises sta-ge heating a mixture of iron ore, suitably sintered or briquetted and a non-coking solid carbonaceous material having gas-forming constituents, along a vertically-ranging course sealed from the atmosphere through which is passes by gravity; by first feeding the mixture downwardly into an annular preheating Zone of relatively large superficial area in said course while directing heated gases centrally upward through said annular zone in heattransfer and physically separated relation to descending solids, next directing the descending solids into a second annular heating zone of lesser superiicial area than the first said zone, subjecting the solids in said second Zone to the heat transfer action of heated gases contacting the central and external bounds of said zone and heattransfer action by conduction of heat through the outer :boundary of the said second annular heating Zone such that the temperature of the mixed solids and reactants is raised to the range of 1800 to 2l50 F., causing evolved gases to travel concurrently with said solids throughout substantially the vertical extent of said second racne, passing said evolved gases into said central area at the bottom of said second zone to permit their ascent in heat transfer relation to the descending material, then directing the descending solids into a third annular heat-transfer zone and then causing relatively cool carrier gases to pass through descendingI solids in said third zone in a direction countercurrent to the solids movement therein to extract heat units and evolved gases therefrom.

The drawing shows a diagrammatic arrangement of apparatus for carrying out this invention wherein the ore and the lignite or the like are in admixture; and

An elongated reaction vessel I is vertically positioned in a combustion chamber 2, the whole being suitably supported by a base 3. Compression springs A transfer the weight of the Vessel I through angles 5 to the base 3 while permitting temperature-induced dimensional changes in the vessel I.

The combustion chamber 2 surrounds the vessel I for the major portion of its length, and said chamber 2 is provided with an inlet 6 for air and fuel and an outelt 'I for flue gases. The reaction vessel l is provided with valves 8, 9 at its upper and lower ends for admitting and discharging solids while maintaining a gas-tight seal.

Inside the vessel I near its lower end is positioned a hollow, cylindrical member I0, closed at its upper end and open at its lower end. The member I0 is spaced apart from the inner wall of vessel l to define an annular reaction Zone Il. A pipe I2 passes through the lower part of the vessel I into the upper part of the member I0 to cause steam or other introduced gases to ll the member I0 and escape into zone II.

Above the cylindrical member I0 in the vessel I is provided a second hollow cylindrical member i3 spaced apart from the vessel I to dene an upper annular reaction zone I4. The second member I3 is spaced apart from the lower member to provide a throat I5 for egress of gases and vapors from the reaction Zones I4 and i5. The

F top lo of member I3 is provided with a pipe I'I to remove evolved gases from the member I3. The pipe Il is vertically positioned in the upper portion of the vessel I and then passes out of the vessel l. A portion of the pipe I'I is surrounded by a jacket IB open at the bottom and closed at the top, into which steam is admitted through an inlet pipe I9.

In carrying out the provisions of this invention, lignite or other solid non-coking carbonaceous material, together with iron ore, preferably briquetted into small pellets, is charged into a hopper 20 at the upper end of the reaction Vessel I and thence through the feed valve 8 into the upper portion of the vertically rangingI reaction vessel I. As will be seen, this portion of the vessel I forms an annular reaction zone of relatively large superficial area and the mixture of lignite or the like and oxidized iron ore is there preheated by heat exchange with the gases leaving pipe I'I and carried to the upper member I3.

Additional heat and water is supplied in the form of steam entering the pipe I9 and passing into the preheating zone through the jacket I8. Thereupon the mixture of lignite or the like and iron ore passes downwardly by gravity into a second annular heat zone III defined by the vessel I and the upper central member I3. In this heating zone, combustion gases formed by burning fuel in the combustion chamber 2 sweep around the vessel I and heat the mixture in the reaction lone I4 to a temperature in the range of about 1800 to 2l50 F. The lignite is rst distilled in the Zone I4 and then reacts with the` steam concurrently traveling downwardly in the presence of the iron oxide to form a mixture of hydrogen and carbon monoxide which in turn acts to reduce the iron oxide content of the ore. Fuel is burned in the combustion chamber 2 surrounding the vessel I by admitting a mixture of fuel and air through the inlet 6 where it passes around the vessel I and emerges as flue gases from the outlet l. In passing down through the annular reaction zone Ill the gases and solids travel concurrently and the gases emerge through the throat I and pass upwardly into the inner portion of the upper member I3 in heat exchange relationship with descending solids and gases of the annular reaction zone I4. The evolved gases andy vapors then passl upwardly through the pipe II and out through the preheating zone to be vented from the apparatus.

After leaving the throat I5 deiinedby the upper member I3 and the lower member I positioned in the vessel I, the solids, including lignite or the like not yet completely'gasied, and the partially reduced iron oxides, then pass downwardly into the annular reaction zone II at a temperature between 1800" and 2l50 F.' The temperature is regulated in part by controlling the combustion in the chamber 2 and in part by adjusting the rate at which solid reactants are fed and discharged through the valves 8A and 9, as well as in part by the admission of steam into the preheating zonev through the pipe I9. Additional control is secured by introduction of steam and other gases as desired through the pipe I 2 into the upper portion of the lower member I0.

In traversing the reaction zone II in the lower portion of the vessel l, evolved gases, steam and carrier gases pass in countercurrent stream to the descending solids. Conditions are adapted in zone I I in accordance with the well-known water-gas reactions to achieve as complete a gasification as possible of the carbonaceous constituents without at the same time reoxidizing the iron ore being reduced. It is to be observed that steam or carrier gases entering the inner portion of the lower member I@ through the pipe I 2 first pass upwardly through the pipe I2 and then downwardly in heat exchange relationship with the materials in the surrounding reaction zone II and thence upwardly through the reaction zone II. By this means, temperature control is greatly facilitated, while the solid materials leaving the vessel through the valve 8 have been deprived of most of their usable heat.

After removal of the solid materials from the vessel through the valve 9, sponge or metallic iron is separated from the discharged solids by magnetic means.

As an example of the operation. of the process for direct reduction of iron ore with simultaneous production of high heating value oxygenated Water gas from admixed raw lignite, the following experimental data obtained from a test in a pilot plant of the same design as that shown in the drawing are cited:

In this test, oxidized magnetic iron ore, briduetted into small pellets, was mixed with raw lignite in ratio of 1:1 and charged into the upper reaction zone I4, wherein the mixture was heated progressively to about 1800 F. before passing into the lower reaction zone II wherein it was further heated in about the same temperature range while in contact with water gas generated in the reaction zone by reactants passing countercuri'ent to the descending solids. The reduced mixture consisting of" metallic iron and fine highash lignite dust was discharged at the bottom while high heating value gas formed by reactions betweenv lignite, steam and oxygen from the iron ore, within reaction zones Ill and l I was removed from the system through heat exchange zones within thev upper member I3 and the pipe I?. The following operating data were recorded:

Rate of feed of lignite,

pounds per hour,v about" 25 Rate of feed of iron ore,

pounds per hour, about- 25 Rate of steam input to upper reaction zone 0 Rate of steam input to lower reaction Zone,

lbs./hr l5 Gas made cubc feet per hour 444 Analysis of gas:

Carbon dioxide percent- 1.4 Carbon monoxide do 40.9 Hydrogen doh 55.6 Methane do 2.1 Specific gravity .480 Heating value, B. t. u. per cubic foot 327 Temperature, bottom of combustion cha-1nber I F 1895 Temperature, middle of combustion chamber F 1855 Temperature, top of' combustion chamber F 1620 Temperature, outlet of furnace do 1410 Temperature, out of recuperator do 84:5 Temperature, gases leaving retort do 515 Temperature, solids leaving bottom of retort The sponge or metallic iron yielded was tested and found to be substantially completely reduced metallic iron;

This application is a division of my applica" tion, Serial No. 589,450, rll'ed April 20, 1945.

Since many apparently widely differing embodiments of the invention will occur to one skilled in thev art, various changes may be made in the method and means described and shown, without departing from the spirit and scope ofl thisinvention.

What is claimed is:-

The endothermic chemical' reaction process, which comprises stage heating a mixture of iron orey suitably sintered or briquetted and a noncaking solid carbonaceous materialv having gasl forming and liqueable constituents, along a vertically-ranging coursev sealed from the atmosphere through which it passes by' gravity; by rst feeding the mixtureA downwardly' into an annular preheating zone of relatively large super- :IicialV area in saidv course while.l directing heated gases centrallyl upward through said annular zone in heat-transfer and physicallyV separated relation to descending solids, next. directing the descending solids into, a second annular heating. zone of lesser superiicialarea. thanthe rst said zone, subjecting the solids in said second zone to the heat-transfer action of heated gases contacting the central and the outer boundary of the said second annular heating Zone such that the temperature of the mixed solids and reactants is raised to the range of 1800 to 2156" F., causing evolved gases to travel concurrently with said solids throughout substantially the vertical extent of said second zone, passing said evolved gases into said central area at the bottom of said second zone to permit their ascent in heat-transfer relation to the descending material, then directing the descending solids into a third vannular heat-transfer zone and then causing relatively cool carrier gases to pass through de- 6 scending solids in -said third zone in a direction countercurrent to the solids movement therein to extract heat units and evolved gases therefrom.

VERNON F. PARRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Trent Oct. 13, 1925 Number 

